1. Field of the Technology
The present disclosure relates generally to data burst communication techniques for mobile communication devices which operate in wireless communication networks.
2. Description of the Related Art
A mobile communication device (e.g. a mobile station or MS) may operate in a wireless communication network which provides for high-speed data communications. For example, the mobile station may operate in accordance with Global System for Mobile Communications (GSM) and General Packet Radio Service (GPRS) technologies. Today, such a mobile station may further operate in accordance with Enhanced Data rates for GSM Evolution (EDGE) or Enhanced GPRS (EGPRS).
EDGE/EGPRS is digital mobile telephone technology that allows for increased data transmission rate and improved data transmission reliability. It is generally classified as a 2.75G network technology. EDGE has been introduced into GSM networks around the world since 2003, initially in North America. EDGE/EGPRS may be used in any packet-switched application, such as those involving an Internet connection. High-speed data applications, such as video and other multimedia services, benefit from EGPRS' increased data capacity.
A mobile station operative in accordance with EGPRS may have multi-slot capability which enables them to use between one (1) and eight (8) time slots for data transfer (see e.g. 3GPP specification). Since uplink, and downlink channels are reserved separately, various multi-slot resource configurations may be allocated in different directions. Mobile stations are categorized into two types based on the multi-slot class that it supports: (1) Multi-slot Classes 1-12, 30-45 (Type 1). These classes have multi-slot capability in the uplink (UL) and downlink (DL) directions and may use this capability (quasi) simultaneously. This group of multi-slot classes may use half duplex or full duplex communication. (2) Multi-slot Class 19-29 (Type 1). This class is less sophisticated than the previous group and, in the current GPRS phase, will use only half-duplex operation. The reason for this limitation may be explained by selecting, for example, multi-slot class 26. In this case, the maximum allowable timeslot in the UL is 4 and in the DL it is 8. Simultaneous transmission and reception of such a magnitude is possible only if the mobile station is capable of transmitting and receiving at the same time. This particular group, however, does not have such capability and the specification limits their operation to half-duplex. (3) Multi-slot Class 13-18 (Type 2). This class is the most advanced group of mobile stations. They have capability to simultaneously transmit and receive (full duplex communication), requiring splitters, duplexers and filters to separate transmit and receive paths.
Table 1 below describes the permitted multi-slot classes within 3 GPP Rel. 6 specification. Again, multi-slot Class 13-18 (Type 2) is the most advanced group of mobile stations and such class is highlighted in Table 1. As illustrated, although the number of allocated receive (Rx) and transmit (Tx) time slots may change dynamically for the mobile station, the total number of Rx+Tx slots within a given frame never exceeds the value “Sum” provided in the Table 1.
TABLE 1Multi-slot Classeswhere(a) = 1 with frequency hopping = 0 without frequency hopping(b) = 1 with frequency hopping or change from Rx to Tx (i.e. MS Type 1) = 0 without frequency hopping and no change from Rx to Tx. (i.e. MS Type 2)(c) = 1 with frequency hopping or change from Tx to Rx (i.e. MS Type 1) = 0 without frequency hopping and no change from Tx to Rx (i.e. MS Type 2)to = 31 symbol periods (this can be provided by a TA offset. i e., a minimum TA valueNA = Not ApplicableParameters shown in Table 1 are defined as follows:
Tta: Tta relates to the time needed for the MS to perform adjacent cell signal level measurement and get ready to transmit. For type 1 MS, it is the minimum number of timeslots that will be allowed between the end of the previous transmit, or receive time slot and the next transmit time slot when measurement is to be performed between, ft should be noted that, in practice, the minimum time allowed may be reduced by amount of timing advance. For type 1 MS that supports extended TA, the parameter Ttn is increased by 1 if TA>63 and there is a change from Rx to Tx. For type 2 MS, it is not applicable.
Ttb: Ttb, relates to the time needed for the MS to get ready to transmit. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected. For type 1 MS, it is the minimum number of timeslots that will be allowed between the end of the previous receive time slot and the next transmit time slot or between the previous transmit time slot and the next transmit time slot when the frequency is changed in between. It should be noted that, in practice, the minimum time allowed may be reduced by the amount of the timing advance. For type 1 MS that supports extended TA, the parameter Ttb=2 if TA>63 and there is a change from Rx to Tx. For type 2 MS, it is the minimum number of timeslots that will be allowed between the end of the last transmit burst in a TDMA frame and the first transmit burst in the next TDMA frame.
Tra: Tra relates to the time needed for the MS to perform adjacent cell signal level measurement and get ready to receive. For type 1 MS it is the minimum number of timeslots that will be allowed between the previous transmit or receive time slot and the next receive time slot when measurement is to be performed between. For type 2 MS, it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.
Trb: Trb relates to the time needed for the MS to get ready to receive. This minimum requirement will only be used when adjacent cell power measurements are not required by the service selected For type 1. MS, it is the minimum number of timeslots that will be allowed between the previous transmit time slot and the next receive time slot or between the previous receive time slot and the next receive time slot when the frequency is changed in between. For type 2 MS, it is the minimum number of timeslots that will be allowed between the end of the last receive burst in a TDMA frame and the first receive burst in the next TDMA frame.
Note that the coding of the timing advance (TA) value (8 bits) is the representation of the timing advance in bit periods; 1 bit period= 48/13 μs. Also, for all the bands except GSM 400, the values 0-63 are valid TA values, and bit 7 and bit 8 are set to spare. For GSM 400, the values 0 to 219 are valid TA values. The remaining values 220 to 255 decimal are reserved.
As apparent, mobile stations may be assigned to or allocated downlink time slots in a variable manner. Preferably, mobile stations may be assigned or allocated a relatively large number of downlink time slots for increased data throughput to the mobile stations.
Referring ahead to FIGS. 4 and 5, what are shown are timing diagrams 400 and 500 for use in illustrating problems associated with assigning or allocating a mobile station a relatively large number of downlink time slots for increased data throughput. Timing diagram 400 of FIG. 4 reveals the structure of a plurality of downlink time slots 402 (top row) and a plurality of uplink time slots 404 (bottom row) of a wireless communication system. Data are communicated between a plurality of mobile stations and a base station of a wireless communication network in a plurality of data bursts contained within downlink and uplink time slots 402 and 404 assigned to each mobile station. Downlink time slots 402 are designated as 0 through 7 in the figure, for a total of eight (8) possible downlink time slots 402 per data frame in the wireless communication system. Also as shown, uplink time slots 404 are designated as 0 through 7 in the figure, for a total of eight (8) possible uplink time slots 404 per data frame in the wireless communication system. In this wireless communication system, the boundaries of each downlink time slot 402 are in exact time alignment with the corresponding boundaries of each uplink time slot 404. Shown as being numerically staggered in relation to the uplink time slots, downlink time slots 0, 1, 2, 3, 4, 5, 6, and 7 have and cover the same time period as uplink time slots 5, 6, 7, 0, 1, 2, 3, and 4, respectively.
Again, data throughput to a mobile station may be increased by increasing the number of downlink time slots 402 assigned to the mobile station. In the example of FIG. 4, five (5) downlink time slots 406 are assigned to the mobile station for data reception (i.e. downlink time slots 0, 1, 2, 3, and 4), two (2) time slots 408 and 410 are utilized for transceiver switching (from receive to transmit mode, and from transmit to receive mode) and obtaining signal strength measurements of adjacent base, station cells, and one (1) time slot 414 is assigned to the mobile station for data transmission (i.e. uplink time slot 4) for each data frame. The following data frame in timing diagram 400 also shows a portion of the next five (5) downlink time slots 416 for data reception (i.e. downlink time slot 0, 1, 2, etc.). The time slot assignment scenario in FIG. 4 would increase data throughput to the mobile station. As apparent, however, increasing the number of downlink time slots 402 assigned to the mobile station correspondingly decreases the number of uplink time slots 404 assigned to the mobile station. Note that, for proper data communications, at least one uplink time slot per data frame should be assigned to and utilized by the mobile station for data transmission from the mobile station. Using conventional data burst techniques in the wireless communication system, however, the time it takes to switch the wireless transceiver of the mobile station from receive to transmit mode, and then back from transmit to receive mode, would have to occupy portions of uplink time slot 414 such that data transmission having proper formatting within uplink time slot 414 would be impossible. Therefore, the time slot assignment scenario of FIG. 4 is unrealistic, unless some special techniques are utilized.
Similarly, timing diagram 500 of FIG. 5 reveals the structure of a plurality of downlink time slots 502 (top row) and a plurality of uplink time slots 502 (bottom row) of a wireless communication system. Data are communicated between a plurality of mobile stations and a base station of a wireless communication network in a plurality of data bursts contained within downlink and uplink time slots 502 and 504 assigned to each mobile station. Downlink time slots 502 are designated as 0 through 7 in the figure, for a total of eight (8) possible downlink time slots 502 per data frame in the wireless communication system. Also as shown, uplink time slots 504 are designated as 0 through 7 in the figure, for a total of eight (8) possible uplink time slots 504 per data frame in the wireless communication system. In this wireless communication system, the boundaries of each downlink time slot 502 are in exact time alignment with the corresponding boundaries of each uplink time slot 504. Shown as being numerically staggered in relation to the uplink time slots, downlink time slots 0, 1, 2, 3, 4, 5, 6, and 7 have and cover the same time period as uplink time slots 5, 6, 7, 0, 1, 2, 3, and 4, respectively.
Again, data throughput to a mobile station may be increased by increasing the number of downlink time slots 502 assigned to the mobile station. In the example of FIG. 5, six (6) downlink time slots 506 are assigned to the mobile station for data reception (i.e. downlink time slots 0, 1, 2, 3, 4, and 5), one (1) time slot 508 is utilized for transceiver switching (from receive to transmit mode), and one (1) time slot 514 is assigned to the mobile station for data transmission (i.e. uplink time slot 4) for each data frame. The following data frame in timing diagram 500 also shows a portion of the next six (6) downlink time slots 516 for data reception (i.e. downlink time slot 0, 1, 2, etc.). The time slot assignment scenario in FIG. 5 would increase data throughput to the mobile station. As apparent, however, increasing the number of downlink time slots 502 assigned to the mobile station correspondingly decreases the number of uplink time slots 504 assigned to the mobile station Note that, for proper data communications, at least one uplink, time slot per data frame should be assigned to and utilized by the mobile station for data transmission from the mobile station. Using conventional data burst techniques in the wireless communication system, however, the time it takes to switch the wireless transceiver of the mobile station from transmit to receive mode would have to occupy a portion of uplink time slot 514 such that data transmission having proper formatting within uplink time slot 514 would be impossible. Therefore, the time slot assignment scenario of FIG. 5 is also unrealistic, unless some special techniques are utilized.
Accordingly, what are needed are improved data burst communication techniques which overcome the deficiencies of the prior art, for increased data throughput, to mobile stations.